There has been hitherto known a data transmission device (MFP) for acquiring personal information from a directory server and carrying out FAX transmission or mail transmission by using transmission destination information (FAX number, mail address or the like) contained in the personal information (see JP-A-2004-274486, for example).
When a user of the data transmission device utilizes transmission destination information, the user inputs a predetermined search condition to the data transmission device to make the directory server carry out a search. The user acquires a search result from the directory server, extracts transmission destination information from the search result and utilizes it for data transmission.